1. Field of the Invention
In the automotive field, final control elements for controlling internal combustion engines are used that keep a control element between a minimal and a maximal position. A typical embodiment uses two spring elements, of which one works in the opening direction and one in the closing direction, and of which, one spring element at a time is not operative in a partial range. The spring acting in the closing direction is typically embodied as a helical or spiral spring, while the spring acting in the opening direction is embodied as a helical spring and as a leaf spring.
2. Description of the Prior Art
Final control elements for controlling internal combustion engines that have a currentless position between a minimal and a maximal position are known for instance from German Patent Disclosures DE 36 31 283 and DE 39 08 596. The final control elements known from these references each include two spring elements, one of which acts in the opening direction and one in the closing direction.
From German Patent Disclosure DE 38 32 400 A1, an apparatus with a control motor for engagement with a transmission element is known. In this reference, an apparatus includes a control motor for engagement with a transmission element. The transmission element is operative between a human control element and a control device that determines the power of a driving machine. The human control element is connected to a rotary member, and the control device is connected to a second rotary member mechanism. A tension spring is also provided, which acts on the one hand on the first rotary element and on the other on the second rotary element, in such a way that the rotary elements seek to execute a rotary motion relative to one another, until a stop of one rotary element meets a stop of the other rotary element. A third rotary element is disclosed, with which the control motor is operatively connected and by which the second rotary element is rotatable. Between the first and third rotary elements there is a coupling, which is inoperative in a certain position of these rotary elements relative to one another. The third rotary element can be restored to a restoring element by means of at least one reverse rotation spring assembly acting directly or indirectly on the third rotary element. The reverse rotation spring assembly can either be operative in only one direction of rotation or, depending on the position of the third rotary element, in either one or the other direction of rotation. The reverse rotation spring assembly comprises at least one reverse rotation spring with two spring ends, of which the first spring end housing is fixedly supported, and the second spring end can act on the third rotary element in a reverse rotation direction via an attachment on the third rotary element.